The Birds: Why the passenger pigeon became extinct

September 3, 2015 10:51 AM

"One hunter recalled a nighttime visit to a swamp in Ohio in 1845, when he was sixteen; he mistook for haystacks what were in fact alder and willow trees, bowed to the ground under gigantic pyramids of birds many bodies deep." In his new book about the passenger pigeon, the naturalist Joel Greenberg sets out to answer a puzzling question: How could the bird go from a population of billions to zero in less than fifty years? (SLNewYorker.)

Previously on MetaFilter: "One hundred years ago today Martha, the last known passenger pigeon, died in the Cincinnati Zoo." (September 1, 2014)

posted by Rangi (48 comments total)

I'm not too big on "oh, back in the day!", but damned if I'm not sorry I was born far, far too late to see a passenger pigeon flock. It sounds like a hell of a thing.
posted by Pope Guilty at 11:12 AM on September 3, 2015 [11 favorites]

There is the notion that the North America that the early settlers saw, in terms of richness of flora and fauna, was not the norm.
Disease and war had done a number on human population, so North America was in a state of boom for many animals when white people first showed up, so there was an unnatural expectation of what the continent actually held.

Is it possible that the pigeon flocks that were recorded were simply echoes of this and that the population would have crashed naturally anyway?

That is to say, if there were billions and billions of passenger pigeons eating every thing in sight, destroying entire forests with their poop, that seems like it would unsustainable in the long term, regardless of human intervention.
posted by madajb at 11:14 AM on September 3, 2015 [22 favorites]

... a puzzling question: How could the bird go from a population of billions to zero in less than fifty years?

From the article: "The short answer is that it tasted good. Also, it was easy to kill and so abundant that it often seemed, in the days before refrigeration, like the quail that fell on the Israelites in Exodus."

Am I missing something?
posted by Greg_Ace at 11:15 AM on September 3, 2015 [2 favorites]

It sounds like they were more like a hideous plague of locusts than adorable city park pigeons. But edible locusts.
posted by JackFlash at 11:16 AM on September 3, 2015 [1 favorite]

The dudes over at Stuff You Should Know did a podcast on these recently, and it a good one.

Is it possible that the pigeon flocks that were recorded were simply echoes of this and that the population would have crashed naturally anyway?

That's actually a pretty strong prevailing theory; there's a little bit of evidence that their population was artificially large about when colonization started.
posted by furnace.heart at 11:17 AM on September 3, 2015 [6 favorites]

It sounds like they were more like a hideous plague of locusts than adorable city park pigeons. But edible locusts.

Locusts themselves are edible! "[They taste like] something between chicken schnitzel, toasted sunflower seeds and prawns… so they say (the author, as a vegetarian, cannot confirm this)."
posted by Rangi at 11:20 AM on September 3, 2015 [7 favorites]

Is it possible that the pigeon flocks that were recorded were simply echoes of this and that the population would have crashed naturally anyway.
I was about to post the same thing. The book "1491" touches on this idea - that the thundering herds of bison, and cod so plentiful you could walk on them across Massachusetts Bay - had grown so huge due to the fact that the humans who had been managing them had all suddenly died off.
posted by jetsetsc at 11:25 AM on September 3, 2015 [10 favorites]

Is it possible that the pigeon flocks that were recorded were simply echoes of this and that the population would have crashed naturally anyway?

I don't remember where I read it, but I do recall a theory that the Native Americans were using "slash and burn" tactics to create farmland in Tennessee/Kentucky, and that they were hunting the shit out of the pigeons. After the europeans showed up, the majority of the native peoples died. So, by the time the Europeans got inland there were billion of pigeons and overgrown forests for Davey Crockett and Daniel Boone to hang out in.

On preview: Maybe it was 1491 like jetstsc mentions
posted by sideshow at 11:30 AM on September 3, 2015 [1 favorite]

But native American people were, at the time, basically at a stone age level of development right? How many pigeons could they have killed?
posted by GuyZero at 11:43 AM on September 3, 2015

Wait, so how were the Native Americans managing/farming the Cod in Massachusetts bay? We don't seem to be able to do that, anymore.

The salmon in the PNW were literally that vast, but it's because there were more of them, than the Native Americans, and the Native Americans weren't daming up every single river with enormous, concrete dams and severely impacting their reproductive cycle. They were consciously taking only a fraction of the fish, but I don't remember fish numbers exploding afterwards.

The, "wildlife will bounce back" idea is one of my fantasies for when humans suddenly disappear from the Earth, but then I think of nuclear power plants going critical and I frown again.
posted by alex_skazat at 11:46 AM on September 3, 2015

But native American people were, at the time, basically at a stone age level of development right? How many pigeons could they have killed?

Turns out an apocalyptic event, like, say a plague that kills off 90% of the population is quite capable of knocking civilization back a few rungs on the ladder.
posted by NoxAeternum at 11:47 AM on September 3, 2015 [21 favorites]

sideshow : So, by the time the Europeans got inland there were billion of pigeons and overgrown forests for Davey Crockett and Daniel Boone to hang out in.

Overgrown fields. VERY important difference. Crocket and Boone needed easy farming to make leisure time for hunting.
posted by IAmBroom at 11:54 AM on September 3, 2015 [2 favorites]

Turns out an apocalyptic event, like, say a plague that kills off 90% of the population is quite capable of knocking civilization back a few rungs on the ladder.

So seriously, I really don't know, but even prior to the arrival of Europeans Americans were not making their own metal tools were they?

Wikipedia indicates there was metalworking going on in central & south America, but "no one has found evidence that points to the use of melting, smelting and casting in prehistoric eastern North America."

At any rate I suppose that regardless of whether you had metal tools or not you could still take kill a lot of birds with arrows and spears if you had enough people. I guess metal knives or arrowheads would not necessarily up the bird killing rate.
posted by GuyZero at 11:57 AM on September 3, 2015 [1 favorite]

GuyZero: But native American people were, at the time, basically at a stone age level of development right? How many pigeons could they have killed?

Two mistakes:

Calling the League of Five Nations "stone-aged" is like calling, I dunno, a brass munitions plant a "bronze age factory".

And it's not the pigeons they could have killed so much as the gigantic ecological upset of removing tens of thousands of top-predators (humans) from the habitat. The turmoil that followed allowed plague-like seasons of carrier pigeons to be possible.

Bible quotes + American memory of the Dust Bowl makes it seem like locust plagues were a periodic occurrence, but in fact the Dust Bowl would have stood out singularly in the memory of a 500-year-old human. So, it's possible swarms of passenger pigeons blackening the sky are a similarly unusual event, but because it occurred so close to their extinction (and in fact promoted their extinction), we believe it was a normal state for that species.

If you think about the biomass necessary to sustain such a bumper crop of pigeons, it seems likely they would have self-corrected shortly anyway - but probably not to extinction.
posted by IAmBroom at 11:58 AM on September 3, 2015 [17 favorites]

How many pigeons could they have killed?

Quite a few I imagine, though not as many as 19th-century Americans. The species that were still around at the time would have been those that had successfully adapted to the pressures of being hunted by native American hunters. Those that didn't adapt were already extinct. Those that did, they might for example have had an increased rate of reproduction to make up for all the mortality from human predation, a balance arrived at over thousands of years, which would leave them ready to explode in numbers when things got disrupted.
posted by sfenders at 11:59 AM on September 3, 2015 [7 favorites]

Parts of Africa currently have a similarly numerous bird, the red-billed quelea. Like passenger pigeons, they also eat everything in their path, and are also regularly compared to locusts.

"A flock of a million quelea, which isn't uncommon, can consume 60 tons of food in a day."
posted by clawsoon at 12:09 PM on September 3, 2015 [3 favorites]

Things I wish had been around long enough for me to see:

Passenger pigeons

Carolina parakeets(due for a centennial post in Feruary 2018)

American chestnuts
posted by TedW at 12:13 PM on September 3, 2015 [3 favorites]

Erm. Am I the only one a bit surprised at the skeletons in environmentalists' closets coda to that piece?
posted by tapesonthefloor at 12:55 PM on September 3, 2015 [1 favorite]

Have researchers modeled the influence of house cats, habitat loss/deforestation, industrial pollution, the arrival European Starlings and other non-native species and of course the introduction of avian flu viruses? While commercial hunting was clearly devastating to the population, I wonder if it was really enough to push the population to extinction or if one of these factors was in play as well. The article doesn't seem to cover this in any depth and I'm too busy to investigate for myself atm, so if anyone knows please share.
posted by humanfont at 12:58 PM on September 3, 2015

"I sang all night, the moon shone on me through the trees
No brothers left, and there'll be no more after me..."
posted by koeselitz at 1:02 PM on September 3, 2015

I wasn't expecting the chimeric duck. Here's a bit more about it.
posted by Devonian at 1:05 PM on September 3, 2015 [1 favorite]

The New Yorker article quotes Greenberg as writing, "a widely held view is that this species could not sustain itself without a giant population." In other words that like, say, penguins, it could not survive in small groups but needed "collaboration on a giant scale." Wikipedia mentions "This was a highly gregarious species – the flock could initiate courtship and reproduction only when they were gathered in large numbers; smaller groups of passenger pigeons could not breed successfully, and the surviving numbers proved too few to re-establish the species." So as its numbers declined due to hunting, deforestation etc., at some point it lost whatever critical mass of population it needed and because doomed even if hunting had then stopped.

I had heard this theory years ago and assumed it was gospel but the quote in the review implies not everybody agrees with it. But I'm not finding anything that contradicts or throws doubt on this it.
posted by beagle at 1:10 PM on September 3, 2015 [1 favorite]

So – eugenics, huh?
posted by koeselitz at 1:14 PM on September 3, 2015

There are such things as traps and nets. Also killing adult birds isn't the only form of predation.

A painstaking researcher, Greenberg writes with a naturalist’s curiosity about the birds, the more than forty-two genera of plants they ate, the crops they favored, and their love of “mast”—the collective name for beechnuts, acorns, and other hard forest fruits that fall in staggered cycles of reproductive boom and bust.

Which sounds to me like the pigeon populations would have been vulnerable to:

1. Competition with Native Americans who also used acorns, beechnuts, and hickory nuts as food staples.
2. Human harvesting of competing species such as deer and wild turkeys.
3. Habitat loss as both Native Americans and colonists cut forests for agriculture.
4. Hardwood harvesting, which was critical for industrial development, changed the ecology of forests, and often displaced native species.
posted by CBrachyrhynchos at 1:18 PM on September 3, 2015 [4 favorites]

the flock could initiate courtship and reproduction only when they were gathered in large numbers; smaller groups of passenger pigeons could not breed successfully

This would certainly explain why the attempt to save them through captive breeding failed miserably. Even if there had been multiple zoos trying it still wouldn't have mattered since their flocks would never have been large enough.
posted by tommasz at 1:18 PM on September 3, 2015 [1 favorite]

the flock could initiate courtship and reproduction only when they were gathered in large numbers; smaller groups of passenger pigeons could not breed successfully

This would certainly explain why the attempt to save them through captive breeding failed miserably. Even if there had been multiple zoos trying it still wouldn't have mattered since their flocks would never have been large enough.

And why "de-extinction" efforts may be doomed.
posted by jetsetsc at 1:22 PM on September 3, 2015 [2 favorites]

If the Native Americans did hunt them I'd be curious to know by what means, because one of the things that made them such easy pickings is they had no fear of man.

This article makes it pretty clear that we went fucking apeshit on them, right to the end:

When the bounty proved too much for a single man or even a single town to use, hogs were loosed to clean the ground of dead pigeons and helpless chirping squabs.

posted by George_Spiggott at 1:22 PM on September 3, 2015 [1 favorite]

If I remember right, the majority of the Great Eastern Forest had been harvested at least once by the end of the 19th century, and a large amount of current National Forest and National Park land dates back to depression-era reserves established because it was cheaper to buy out marginal farms than to keep them running. So the loss of mature, native trees may have been a factor.
posted by CBrachyrhynchos at 1:23 PM on September 3, 2015 [1 favorite]

What I got from the New Yorker article was that two simultaneous technological/economic developments doomed the passenger pigeon:

1. An explosion in logging, that eliminated the forests the pigeons needed for food.

2. The development of railroads (and real-time cross-continent communication with the telegraph), that gave pigeon hunters both amateur and professional the ability to track the great flocks and follow them wherever they went. So there was no respite for the passenger pigeons anymore, they were hunted in every season and every place.

If both of these things hadn't happened at the same time, the species might have survived. Although no doubt in diminished numbers.
posted by Kevin Street at 1:27 PM on September 3, 2015 [1 favorite]

George_Spiggott: “If the Native Americans did hunt them I'd be curious to know by what means, because one of the things that made them such easy pickings is they had no fear of man.”

From Wikipedia – it's about Wikipedia-quality, but I can't find better at the moment:

The passenger pigeon was an important source of food for the people of North America. The Native Americans ate passenger pigeons, and tribes near nesting colonies would sometimes move to live closer to them and eat the juveniles. The juveniles were killed at night with long poles. Most Native Americans were careful not to disturb the adult pigeons, and instead ate only the juveniles as they were afraid that the adult pigeons might desert their nesting grounds; in some tribes disturbing the adult pigeons was considered a crime. Away from the nests, large nets were used to capture adult pigeons, sometimes up to 800 at a time. Among the game birds, passenger pigeons were second only to the wild turkey in terms of importance for the Native Americans living in the southeastern United States. The bird's fat was stored, often in large quantities, and used as butter.

posted by koeselitz at 1:32 PM on September 3, 2015 [6 favorites]

It is worth noting that, even if a species is successfully revived, there may be knowledge that was passed from animal to animal (like some aspects of hunting behavior with cats) that may still be irretrievably lost, which may be necessary, or at least very helpful, for survival.
posted by JHarris at 1:46 PM on September 3, 2015 [2 favorites]

Still, the history of the bison is cause for some hope. If the genetic engineers can bring back an animal with enough species-specific genes to be called a proper passenger pigeon (an open question at this point, but a fascinating one), then it might follow the same path as the bison. Both species were wiped out at the same time for mostly the same reasons, and at the worst point there were only about 600 bison left. But the buffalo was saved from extinction by conservationists, and while they're not thriving in their original numbers today, the bison are certainly not extinct. A revived passenger pigeon species might have similar success.
posted by Kevin Street at 1:55 PM on September 3, 2015 [2 favorites]

As Kevin Street notes, the bison were saved from extinction, but just barely. Humans (almost exclusively whites) brought the population from 80 million in 1800 to just 500 a century later.

Similarly, the beaver went from somewhere near 200 million to only 100,000 by 1900, mostly in Canada. The eurasian beaver had been hit even harder, and was down to about 1200.

The argument that the pigeon population was artificially high, doesn't invalidate that it was made extinct, and only intervention has saved other species. The book The Sixth Extinction notes that since the arrival of humans, the number of species that has gone extinct has skyrocketed from the "natural background" extinction rate.

Recent studies put the background rate for mammals at 1 species per 1,000,000 years. In the past 500 years, 80 mammals species have gone extinct. For birds, the background rate is about 1 species per 100 years. At present, we're averaging a loss of 1 bird species per year.
posted by CheeseDigestsAll at 2:19 PM on September 3, 2015 [2 favorites]

It is worth noting that, even if a species is successfully revived, there may be knowledge that was passed from animal to animal (like some aspects of hunting behavior with cats) that may still be irretrievably lost

Out of curiosity, which hunting behaviour is this? From what I understand, domestic cats seem to revert to predatory type pretty effectively if they go feral.
posted by acb at 2:37 PM on September 3, 2015

How could the bird go from a population of billions to zero in less than fifty years?

They were clubbed and shot, netted, gassed, and burned. Until there was nothing left but miles of empty nests. Or so I've heard.
posted by Alvy Ampersand at 2:50 PM on September 3, 2015 [1 favorite]

Hunting behavior might be a bad example because it's so instinctual but think tool use like birds dropping rocks on shellfish or shellfish on rocks. I think tool use is decidedly and distinctly learned from animal to animal for what we've observed thus far. No reason it can't be independently figured out again but how long does it take and does the already pressured near extinct species have a chance at recovery without their overall tribal wisdom?
posted by aydeejones at 2:56 PM on September 3, 2015 [3 favorites]

In this case the most likely learned behavior resurrected pigeons would be missing is the location of mast. That is, the location and timing of when particular groves of trees produce the most acorns and other food. It's unlikely that the birds would have this kind of knowledge "hardwired," because trees exist on a shorter timescale than evolution can handle.

For example, an animal like the Green Turtle can evolve a hardwired instinct to migrate to Ascension Island because the island isn't going anywhere anytime soon. Ascension is slowly getting further away from Brazil, but countless generations of turtles can breed there in the time it takes to move a few miles. However, the trees that Passenger Pigeons depend upon are growing in different places on a timescale measured in decades, as they're burned by fires, hit by pests and plight, flooded out or logged in some spots and regrowing in others.
posted by Kevin Street at 3:50 PM on September 3, 2015 [3 favorites]

Turns out an apocalyptic event, like, say a plague that kills off 90% of the population is quite capable of knocking civilization back a few rungs on the ladder.

To clarify, you're referring to the plague-like European invasion of NA and its effect on Native civilizations, right?
posted by five fresh fish at 4:18 PM on September 3, 2015

No, literal plague. The Indians were highly susceptible to European diseases, particularly measles.
posted by bracems at 4:38 PM on September 3, 2015 [3 favorites]

Another barrier for de-extinction are the dependencies an organism may have on its micro-biome and some of those organisms may also be extinct. We are only beginning to understand this dimension of biology
posted by humanfont at 5:37 PM on September 3, 2015 [1 favorite]

Erm. Am I the only one a bit surprised at the skeletons in environmentalists' closets coda to that piece?

No, I found myself thinking: "WTF does this have to do with pigeons?"
posted by MikeMc at 6:19 PM on September 3, 2015

Just want to take this opportunity to link the beautiful passenger pigeon mural we have just a few miles from the Cincinnati Zoo. It is even way more beautiful in person.

The Cincinnati Zoo itself has a little shrine to Martha -- although I understand her remains are somewhere else (Smithsonian maybe?) there's a good exhibit about threatened species since the passenger pigeon extinction.
posted by mostly vowels at 6:24 PM on September 3, 2015 [3 favorites]

No, literal plague. The Indians were highly susceptible to European diseases, particularly measles.

Same difference. Just wanted to be sure we weren't talking about a bird plague.
posted by five fresh fish at 6:26 PM on September 3, 2015 [1 favorite]

So the loss of mature, native trees may have been a factor.

That's what extincted the Ivory-billed woodpecker around the same time (and nearly so the Red-cockaded woodpecker, although it's still hanging on in remnant populations).
posted by junco at 6:52 PM on September 3, 2015 [1 favorite]

her remains are somewhere else (Smithsonian maybe?)

Martha is indeed in the Smithsonian. According to this, she 'flew' back to Cincinnati in 1974 for a building dedication.
posted by LeLiLo at 9:04 PM on September 3, 2015 [1 favorite]

It sounds like they were more like a hideous plague of locusts than adorable city park pigeons. But edible locusts.

Locusts themselves are edible! "[They taste like] something between chicken schnitzel, toasted sunflower seeds and prawns… so they say (the author, as a vegetarian, cannot confirm this)."
posted by Rangi at 11:20 AM on September 3
[7 favorites −] Favorite added! [!]

I can confirm that locusts and are actually pretty tasty. I've had them as a snack and would do it again if I had the opportunity.
Lime juice, salt and a nice beer to wash it down.
posted by Katjusa Roquette at 10:43 PM on September 3, 2015

Metafilter: I wasn't expecting the chimeric duck.
posted by rum-soaked space hobo at 8:17 AM on September 4, 2015 [1 favorite]

I find it strange that people are looking for reasons like logging or biological rebound to explain demise of the passenger pigeon. People used words like "uncountable" and "they blackened the sky" to express their awe of the size of bird flocks, but the reality is that there are finite numbers of birds (whales/turtles/lions).

By the way, people are still at it: Migrating birds around the Mediterranean (caution: gruesome images) are being killed in the millions every year. Albania has been the model for casual poaching of all kinds of birds. We're basically standing around watching humans with guns wipe out entire species.
posted by sneebler at 8:38 AM on September 5, 2015 [2 favorites]